/**
* Perform some operations before adding data into Todo set
* The new and reverse direction is removed from _globset, because we are sure
* it doesn't need to be checked again
* Also, remove reverse direction from _tbdset
* This is the 'core' part so the graph seaching won't enter any tile twice
*
* @param t1 tile we are entering
* @param d1 direction (tile side) we are entering
* @param t2 tile we are leaving
* @param d2 direction (tile side) we are leaving
* @return false iff reverse direction was in Todo set
*/
static inline bool CheckAddToTodoSet(TileIndex t1, DiagDirection d1, TileIndex t2, DiagDirection d2)
{
_globset.Remove(t1, d1); // it can be in Global but not in Todo
_globset.Remove(t2, d2); // remove in all cases
assert(!_tbdset.IsIn(t1, d1)); // it really shouldn't be there already
if (_tbdset.Remove(t2, d2)) return false;
return true;
}
